Food irradiation : Basic Facts, Advantages, Main techniques

1. Food Irradiation : Basic facts, advantages and main
Techniques

2.  Spread of diseases due to microbial contamination of food is a serious threat for
consumer health
 Negative impact on economic prosperity of countries
 Global trading demands to ensure quality and safety of the traded food items
 Food irradiation is a promising technology that eradicates the threat of microbial
contamination while maintaining nutritional quality of food.
 There has been an increase in consumer acceptability in last two decades, but
consumer still has negative perception towards safety and quality of irradiated food

3.  Radiation may considered as a form of energy. We receives natural
form of radiation from the sun and the environment
 Ionizing radiation is used for food irradiation purpose.
 Ionization radiations are referred to those radiations, which interact
with matter and thus enable them to lose electrons that further results
in ion formation.
 In general gamma-rays, X-rays and electron beam are used that are
having higher energy capable to eject electrons from target atoms,
leading to the ionization of molecules.
 Ionizing radiations are strong enough to break chemical bonds of target
molecules like DNA and may alter the regular cells mechanism
Food irradiation process

4. Irradiation facilities comprises of
Radiation source
Shielding to protect personnel from radiation exposure: Includes thick walls of
concrete and a pool of water (6m deep) where the radiation source is kept while
it is not used
Radiation chamber : food /boxes exposed to radiation
Product-transporting conveyor:
synchronized with the exposure of the product to the radiation source.
Efficient air evacuation system: removes the ozone formed by the reaction of
oxygen with free radicals generated during the food irradiation process.
Storage area
Loading area

5. Tote box irradiator (Courtesy of MDS Nordion).

6. Three type of radiation sources used
Gamma Ray Irradiation E-beam irradiation X-Ray Irradiation
Gamma rays emitted from a
radioactive element is used
High-energy electron beams are
emitted form an electron gun
generated when high-velocity electrons are
bombarded on metal (tungsten or tantalum)
and collision generates X ray photons
Photons of Gamma ray possess higher
frequency and higher energy
Lesser energy Shorter wavelength (lesser than 100 nm)
and high frequency
Penetrate deeply (many feet) in target
material (food )
Penetration depth is much
shorter (an inch or few cm)
Highly penetrative (30-40 cm )
Cobalt 60 and Cesium 137 used as
radioactive source
Induces similar effect like gamma
ray irradiation without involving
radioactivity
No need of radioactive source
Cesium 137 is discouraged being
highly soluble in water and risk of
contamination in surrounding
Used to radiate the thin layers of
food
Used for radiation of food products packed
in boxes
Cobalt 60 is mainly used and produces
gamma rays having energies as 1.17
and 1.33 MeV.
Energy level in the range 5 to 10 MeV
Both X rays and E beam are generated by linear accelerator

7. Advantages
Cold process does not induces
temperature changes maintains
freshness and quality of food
Does not leave any toxic chemicals
residues like chemical fumigants
Irradiated food can be stored for
comparatively longer time under
normal temperature conditions
( Increased shelf life)
Limitations
Many types of foods not suitable for radiation
and needs optimized dose level
Cannot eliminate the chemical contaminants
such as pesticides and toxins already present
Stringent safety protocols to avoid radiation
hazard in surroundings
 Food irradiation offers the decontamination of pre-packaged (eg. Ready to eat food) and helps in maintaining
better hygiene of food items
 Radiation processing of food must be accompanied by good hygiene practices so as to avoid re-growth of
microorganism by accidental contamination.
Advantages and limitations

8. Process Dose level (kGy)
Low dose
applications
(< 1 kGy)
Sprout inhibition of tubers, bulbs, rhizomes
Delay in ripening of fruits
Insect disinfestation of cereals, legumes and their products
Medium dose
applications
( 1 - 10 kGy)
Shelf life improvement of meat, fish, fruits and vegetables
Elimination of pathogens in various foods
Hygienization of spices
High dose
applications
( >10 kGy)
Sterilization of packaged food
 Dosimetry is the key to the successful irradiation of food that helps in application of optimized dose to food in
accordance with the imposed legislations
 Absorbed dose is referred to the amount of radiation energy absorbed by food material when it was exposed to
radiation. The absorbed dose is measured by the residence time of food items placed in irradiation position
 Gray (Gy) and kGy (kilo gray ) are internationally acceptable units of radiation dose measurement
 1 Gy = 1J/kg; 1 kGy = 1ooo Gy

10.  Radiation Pasteurization ( microbial decontamination and pathogen inactivation)
High-dose irradiation kills maximum spoilage and pathogenic bacteria (E. coli, Salmonella etc. ) and their spores in food
 Sprout Inhibition
Very-low-dose irradiation treatment inhibits (by altering biochemical reaction) the sprouting of vegetables such as potatoes,
onions and garlic
 Retardation of Ripening
Low irradiation doses delay the postharvest ripening of many fruits (Joanne Liou, 2020).
 Radiation sterilization
Used to sterilize various food items such as for NASA’s astronauts, and for patients with impaired immune systems, Military
rations, food for outdoor enthusiasts (campers, mountain climbers, sailors, etc.) carry safe, nutritious and ready to eat food
that requires no refrigerated storage.
 Phyto-sanitary quarantine measures/disease control :
processes used for disinfestation of insects and pests,
Radiation used disinfect agricultural commodities such as fruit fly in mango

11.  Radura logo is accepted internationally as symbol to indicate that irradiated
food. Internationally Codex and FDA has approved the mandatory use of
radura symbol on irradiated food items, followed by statement “treated by
radiation” or “treated with radiation.
 According to the provisions of PFA Rules (India) all types of irradiated food in
India shall also be labelled with Radura logo
 Re-radiation of food
 Re-radiation of food is not permitted except for few exceptional cases
 such as re-infestation of foods like cereals, pulses and dehydrated foods
 Sometimes full dose of radiations is partly given in steps to get the desired effect.
Radura logo

12.  Not all foods are fit to be irradiated.
 Shelf life extension by food irradiation is superior to thermal processing and maintaining
the nutritional value of foods.
 Safety of irradiated food has been studied on a wide scale and few nutritional deficiencies
have been reported.
 As was believed earlier, there is no concrete proof to support the idea that radiolytic
products can cause cancer or other degenerative diseases.
 People associate ionizing radiation with cancer and consider irradiated food as equally
hazardous. This is a misconception that must be eradicated by proper education.
Conclusion

13.  Anuradha Prakash, Jose de Jesu´s Ornelas-Paz (2020) Irradiation of Fruits and Vegetables, Postharvest
Technology of Perishable Horticultural Commodities. https://doi.org/10.1016/B978-0-12-813276-0.00017-1
 M Elena Castell-Perez and Rosana G Moreira, (2020) Irradiation and Consumers Acceptance, Department
of Biological and Agricultural Engineering, Texas A&M University, College Station, TX, United States
 Nancy Hart, (2012) Irradiation Opens the Door for Indian Exports,
https://www.iaea.org/newscenter/news/irradiation-opens-the-door-for-indian-exports
 Joanne Liou, (2020) Phytosanitary Treatments Using Irradiation for Fruit Fly Pests Gain
Ground,https://www.iaea.org/newscenter/news/phytosanitary-treatments-using-irradiation-for-fruit-fly-
pests-gain-ground
 Arun Sharma, P. Madhusoodanan, (2012), Techno-commercial aspects of food irradiation in India,
Radiation Physics and Chemistry 8, 11, 208–1210.
 Images from Google (Varied Source)